This core consists of a central breeding and typing facility to coordinate the maintenance and distribution of mice used by investigators of the Center. The mice to be housed in this facility are explicitly defined. The maintenance of transgenic mice is critical to this Center, and the need for such a core is well justified with 5 of the 6 projects utilizing genetically modified mice. Therefore, it is appropriate to maintain a transgenic mouse Core within the Center. The level of mouse activity described in the application justifies the hiring of someone to manage the colonies and type offspring (particularly once new lines of mice are being generated). Unfortunately, with the information provided, it is difficult to estimate how many mice need to be genotyped over a given period, what services are already provided by the Comparative Medicine staff as part of their per diem charges (e.g. is colony management part of that charge?), or to what extent the hiring of such a position reduces per diem charges. Nevertheless, given that the Core is maintaining both single and double transgenic mice, the centralization of screening is a prudent move. This will ensure quality (validity of genotypes) and availability of mice to the members of the Center.